Many different factors may be considered when a fan is selected for use with a cooling system of a machine. For example, efficiency, noise and size configurations may be very important factors when selecting the configuration of a fan. Thus, different machines and operating environments may require different fan configurations.
Generally, fans may be made through a wide variety of molding processes that form the blades and hub as a single piece. Consequently, each different configuration of a fan may require its own mold. Additionally, each mold may be a very costly tool and stocking multiple fans may require significant warehouse space. Further, all of these costs and different fan configurations may affect part availability and the logistical costs of supporting a wide variety of different fan configuration.
To provide some adjustability, U.S. Pat. No. 3,545,884 discloses an adjustable fan blade construction where each blade is bolted through a hub to a back plate. The fan blades of the '884 patent can be easily rotated to a desired orientation and rely on centrifugal forces and friction to maintain the desired orientation. Consequently, the blades of the '884 patent may be inadvertently reoriented to an undesirable orientation when a force, such as flying debris, is applied to a fan blade that overcomes the centrifugal forces and friction.
The present invention is directed to overcome one or more of the problems as set forth above.